#include <stdio.h>

int main()
{
    int x = 0,y = 0;
    unsigned int rows = 0;


    printf("Enter the number of rows = ");
    scanf("%u",&rows);

    for(x=1; x <= rows ; ++x)
    {
        // Print star
        for(y=x; y <= rows; ++y)
        {
            printf("*");
        }
        // Print spaces
        for(y=1; y<=((2*x)-2); ++y)
        {
            printf(" ");
        }
        for(y=x; y <= rows; ++y)
        {
            printf("*");
        }
        // Print new line
        printf("\n");

    }

    // Loop to print lower half of the pattern
    for(x=1; x <= rows ; ++x)
    {
        for(y=1; y <= x; ++y)
        {
            printf("*");
        }
        //print space
        for(y=((2*x)-2); y<((2*rows)-2); ++y)
        {
            printf(" ");
        }

        //print star
        for(y=1; y <= x; ++y)
        {
            printf("*");
        }

        printf("\n");
    }
    return 0;
}

Output: